The notion of P-homomorphic signatures, introduced by Ahn et al. (TCC 2012), generalizes various approaches for public computations on authenticated data. For a given predicate P anyone can derive a signature for a message m′ from the signatures of a set of messages M , as long as P(M,m′) = 1. This definition hence comprises notions and constructions for concrete predicates P such as homomorphi...

We construct charged and rotating asymptotically Schrödinger black hole solutions of IIB supergravity. We begin by obtaining a closed-form expression for the null Melvin twist of a broad class of type IIB backgrounds, including solutions of minimal five-dimensional gauged supergravity, and identify the resulting five-dimensional effective action. We use these results to demonstrate that the nea...

We show that eleven-dimensional supergravity backgrounds with thirty one supersymmetries, N = 31, admit an additional Killing spinor and so they are locally isometric to maximally supersymmetric ones. This rules out the existence of simply connected eleven-dimensional supergravity preons. We also show that N = 15 solutions of type I supergravities are locally isometric to Minkowski spacetime. T...

We study Lorentzian wormholes in the ghost-free bigravity theory described by two metrics, g and f. Wormholes can exist if only the null energy condition is violated, which happens naturally in the bigravity theory since the graviton energy-momentum tensors do not apriori fulfill any energy conditions. As a result, the field equations admit solutions describing wormholes whose throat size is ty...

Editorial "Admit medical" As the fog of uncertainty surrounding the purchaser/provider relationship in the restructured health service begins to clear, many doctors responsible for providing acute services find that darkness has already fallen. For those who are charged with managing acute medical admissions to hospital, difficult nights finding beds lie ahead. Hospital physicians and referring...

In pure Einstein theory, Ricci flat Lorentzian 4-metrics of Petrov types III or N have vanishing counter terms up to and including two loops. Moreover for pp-waves and type-N spacetimes of Kundt's class which admit a non-twisting, non expanding, null congruence all possible invariants formed from the Weyl tensor and its covariant derivatives vanish. Thus these Lorentzian metrics suffer no quant...

In this document, I outline a few challenging algorithmic problems arising in my research on optimal transportation. I have attempted to pose these problems in “discrete” language. It easily could be the case that they admit straightforward solutions— which is great news!—or that you can do little more than the obvious algorithm. Any and all guidance from members of the theory community is welc...

We show that all branes admit worldvolume domain wall solutions. We find one class of solutions for which the tension of the brane changes discontinuously along the domain wall. These solutions are not supersymmetric. We argue that there is another class of domain wall solutions which is supersymmetric. A particular case concerns supersymmetric domain wall solutions on IIB D-5-and NS-5-branes.

In pure Einstein theory, Ricci flat Lorentzian 4-metrics of Petrov types III or N have vanishing counter terms up to and including two loops. Moreover for pp-waves and type-N spacetimes of Kundt’s class which admit a non-twisting, non expanding, null congruence all possible invariants formed from the Weyl tensor and its covariant derivatives vanish. Thus these Lorentzian metrics suffer no quant...